1. Field of the Invention
This invention relates to agricultural equipment, such as a combine, for harvesting and threshing a crop, and, more particularly, to an apparatus for use on a combine to continuously monitor clean crop yield as the combine traverses a mature field, as to assist in the generation of a digitized field yield map.
2. Background Art
Fields in which crops are planted rarely have a homogeneous soil composition. Different soil types have a different ability to retain water, nutrients, pesticides, herbicides, etc. Consequently, if uniform application of fertilizers, pesticides, herbicides, and water is carried out, there will be a varied crop yield throughout a given field. This problem induced the development of customized soil and crop treatment, which has been a very high priority research area in the agricultural industry over the last decade.
Early attempts at customizing soil and crop treatment involved manual plotting of the field, monitoring of soil type and condition, and yield monitoring. Of late, field mapping has become substantially more sophisticated. Computer assisted mapping techniques, together with satellite tracking, are commonly used. Crop yield can now be very precisely mapped. In subsequent growing seasons, this yield information can be utilized to custom treat virtually all portions of a field to maximize overall yield. This concept is explained more fully in U.S. Pat. No. 4,630,773, to Ortlip, assigned to Soil Teq., Inc.
While yield maximization has been prompted in good part by economic considerations, environmental concerns regarding chemical application have made even more acute the need for effective field mapping. Further, government regulations have necessitated changes in and/or modifications to certain farming techniques. Still further, the mere shortage of fertile fields in certain geographic areas has dictated the need for maximizing crop yield.
A critical aspect of field mapping is the accurate monitoring of the crop yield. Heretofore, a wide range of different techniques has been developed to monitor crop yields.
One such system employs a gamma ray emitter and detector. Conveying grain passes between the emitter and the detector through a measuring gap. The grain blocks the rays to the detector. The number of rays reaching the detector is translated into a flow volume amount, which can be used to generate a yield map. The principal problem with this system is that there are strict controls placed on gamma ray emission in the United States. Depending upon the construction of the system, it may be illegal f or use in the United States. A system, in accordance with the above, is currently being sold by Dronningborg Maskinfabrik A/S, in Germany.
Another yield sensor is currently available through Acu-Grain in Great Falls, Mont. Acu-Grain's system employs a pivotable flap at the output end of an unloading auger. The degree of pivoting of the flap determines the flow volume, which can then be correlated with other data to generate a yield map. This system, as all systems utilizing moving parts, is prone to failure. In normal harvesting and threshing operations, severe conditions are encountered. Dirt, dust, moisture and chemicals all contribute to premature equipment failure. In addition to the problem of corrosion from chemicals and moisture, buildup of dirt, particularly in damp environments, can effectively reconfigure parts and potentially block the range of movement of parts and, in the case of Acu-Grain's system, the pivoting flap. A buildup in material, on the face of the flap on which the discharging crop impinges, results in an increased pivoting movement for the flap for a given flow volume. This results in a false reading of a larger than actual flow volume. If this buildup is progressive, no compensation can be made and the information generated through the flap monitoring may be meaningless.
Another currently available system was jointly developed by Ford-New Holland, in Belgium, and the Agricultural Engineering Department of the Katholieke Universiteit Leuven. This system utilizes a curved plate which intercepts grain discharging from a clean grain elevator. The grain impacting the curved plate causes deflection thereof, which deflection is sensed and used to determine the flow volume by converting the plate displacement to a flow volume number. The frictional forces between the grain and plate are also worked into the flow volume calculation. The drawbacks with systems utilizing moving parts are present in this system as well.
Another system has been devised by Claydon Yieldometer, Ltd. in Suffolk, England. Claydon's system employs a catch bin to collect discharging grain. The bin is repeatedly filled and dumped. The interval between filling is used to determine the flow volume. Accumulation of grain, or other material within the bin, results in a reduction of the capacity of the bin, which results in inaccurate flow volume measurements. The problems associated with moving parts are also present in the Claydon structure. Still further, retrofitting of the Claydon structure to conventional combines is very expensive to accomplish.
Another system currently under development at Kansas State University uses an auxiliary discharge auger, which is added to a conventional combine. The auger is pivoted and filled at its proximal end. The distal end of the auger is suspended by a load cell. The load cell will detect a difference in the flow volume by detecting a difference in weight at the distal/discharge end of the auger. Because a fairly large accessory must be added to the combine, there are space problems associated with this construction. Further, the aforementioned problems, associated with moving parts, exist.
Other systems are under development to sense the volume of grain in a combine bin. One such system uses an ultrasonic sensor to determine the depth of grain in the bin. Another such system uses sensors at different heights to alert the user to the changing volume of grain in the combine bin. Both systems' accuracy depends upon the combine's being on substantially level terrain.
A further system under development monitors current to a motor that drives a clean grain conveying system in the combine. Flow volume/rate is directly related to the current draw for the motor.
Another system employs a potentiometer to measure batch volume. The accumulation for a given area harvested is determined and a flow rate is calculated therefrom and continuously plotted. The problem with this type of system is that it is sensitive to a change in attitude of the combine.
John Deere currently has a system that determines the speed of the clean grain elevator and the volume of material on each paddle on the grain elevator through electric eyes positioned at the top and/or bottom of the clean grain elevator. The system uses this data to compute the yield. Buildup of material on the paddles may give false readings. Generally, the required accuracy is difficult to achieve with such a system.
Generally, the above systems do not afford an economically feasible yield measuring device that is both accurate and reliable, particularly under severe operating conditions as normally encountered in the farming environment. Another problem is that certain of the above systems operate effectively only with the combine on level ground. Significant inclination of the combine, as may occur on frequently encountered sloped or hilly terrain, may compromise the accuracy of such systems, or make the data generated thereby altogether meaningless. A still further problem with certain of the systems described above is that they may undesirably alter the normal conveyance of crop through and out of the combine.
Several of the above systems came to the attention of the applicants through various trade association meetings. To the knowledge of the inventors, some of these systems are still under development and do not constitute prior art. However, all systems have been discussed to show the recent flurry of activity in yield monitoring and the wide range of proposed solutions to the problems encountered in yield monitoring.